Sea Grant has released an Oil Spill Science Outreach publication discussing examples of how oil and dispersants might affect Gulf of Mexico fisheries to help natural resource managers maintain healthy Gulf of Mexico ecosystems and protect the livelihoods of the people that depend on them.
The bulletin is found here
Because oil and water don’t mix easily, oil droplets in the ocean environment tend to aggregate into larger masses, which hinders microbial degradation. Chemical dispersants used for oil spill response contain water-soluble and oil-soluble components that adhere to oil droplets and increase the oil and water’s compatibility, allowing oil to disperse more easily into the water column and enhancing microbial consumption. However, because chemical dispersants require constant energy input from waves, wind, and currents to keep the oil dispersed, they typically only slow oil’s coalescence rather than prevent it.
Chris Keller is developing a dispersant system that combines silica nanoparticles and polymer surfactants and doesn’t require energy input to generate stable oil emulsions. His goal is to identify which combination of these compounds will maximize oil entrapment and dispersion while minimizing harm to marine life.
Chris is a Ph.D. student with Tulane University’s Department of Chemistry and a GoMRI Scholar with the project Designing Nanoparticle-Based Dispersants with Improved Efficiency and Biocompatibility.
His Path
Chris’s interest in science began with his Mandeville, Louisiana, high school chemistry teacher, whose passion for science and its ability to change the world inspired him. He discovered a knack for scientific research while performing basic lab experiments, often modifying the experimental conditions for efficiency. His interest in chemistry eventually evolved into a passion for polymer science.
As an undergraduate polymer science student at the University of Southern Mississippi, Chris investigated the drug delivery applications of different biopolymers in Dr. Daniel Savin’s polymer science lab. He recalls assisting Kyle Bentz, who was then a graduate student in the lab, with his GoMRI-funded research on nanoparticle-based oil dispersants. The research held great significance to Chris, who is from the Louisiana coast, where oil spills and chemical dispersants can affect the local ecosystem and marine life for years. “When I was accepted to Tulane University as a Ph.D. student, little did I know that I would be continuing that same GoMRI research under the direction of Dr. Scott Grayson,” said Chris. “By researching alternative methods to cleanup oil spills, I feel that I am contributing to measures that can help lessen their impacts and ensure that an oil spill isn’t a defining event for a region’s ecosystem.”
His Work
Chris is continuing the research of Dr. Kyle Bentz and Dr. Muhammad Ejaz investigating polymer-modified silica-based nanoparticles as a new system of oil dispersants. Chris’s team hypothesizes that once the nanoparticle system entraps the oil, the oil’s density will change so that it floats to the ocean surface for collection via skimming. This process could be repeated as many times as necessary to help spill response efforts. Chris is designing the nanoparticle system and observing the nanoparticles’ reactions with unimolecular micelles (single-molecule surfactant polymers that don’t require energy input to generate stable oil emulsions).
The nanoparticle system is made up of a silica-based core with a copolymer chain attached to it that contains both hydrophobic (oil-soluble) and hydrophilic (water-soluble) polymer molecules. The hydrophobic polymer drives the entrapment of oil while the hydrophilic polymer helps disperse the oil into the water column. Chris has found that there is a delicate balance between the ratio of these two polymers that dictates if the system will exhibit the right properties for real-world application. For example, too many hydrophobic molecules could trap oil too quickly, changing the oil’s density so that it rises to the surface earlier than desired, but too many hydrophilic molecules could slow the rate of oil entrapment and reduce the amount of oil that disperses. Too many polymer molecules overall could create particles that are too large to effectively disperse the oil and may affect marine organisms.
So far, Chris has observed preliminary evidence of oil entrapment and established the minimum number of hydrophilic molecules required to disperse the oil particles in water (up to tens of milligrams per milliliter of water). He is currently adjusting the ratio of hydrophobic and hydrophilic molecules to identify combinations that will return the same or better results. To do this, he tests various nanoparticle-micelle mixtures under an inert (not chemically active) nitrogen atmosphere and observes their reactions over time. He examines if simple shaking will disperse the modified particles in water and, if so, records what concentrations are needed to prevent the particles falling to the bottom of the test vial. Each reaction’s success is determined by the amount of polymer that effectively attaches to the nanoparticle surface. He uses a centrifuge to isolate the nanoparticle system and collect the free polymers that did not attach during the reaction. Analyzing the unattached polymers can provide a rough approximation of the size of the polymers that attached to the nanoparticle surface.
Chris sends batches of different polymer-modified nanoparticles to collaborating labs to be analyzed for toxicity and effectiveness in entrapping oil. He constantly adjusts his experimental set up based on his colleagues’ findings on the different formulations. “At the end of the day, it’s about a real-world application. Their results help me adjust the polymer makeup to find a system that will meet our goal: the most oil entrapment with the least environmental impact,” explained Chris. “Furthermore, Dr. Savin’s lab at the University of Florida is developing a different polymer-modified nanoparticle system to test against mine to see which one yields better results.”
Once the new dispersant system’s design is complete, Chris will fine-tune the system so that industry can scale it up for real-world application. While the system is being developed with oil spill mitigation in mind, there are other potential uses of the team’s nanoparticle dispersant system. “Future applications other than dispersants are going to largely depend on how ‘biofriendly’ we can make these,” explained Chris. “For example, an undergraduate student working on his senior thesis under my guidance is examining the use of sugar-based nanoparticles. If we can utilize a different core such as sugar instead of silica, I think we could potentially see some use as drug carriers or filtration devices later down the line.”
His Learning
Dr. Grayson taught Chris to take his research one goal at a time and emphasized collaboration’s important role in achieving those goals. Being a part of the GoMRI community keeps Chris mindful of the broader implications of his research. For example, Chris’s close focus on his laboratory research sometimes caused him to forget that, while his research has applications for oil spill response, research contributing to other applications is just as important. “When I go to the Gulf of Mexico Oil Spill and Ecosystem Science conference, I get to see the other researchers’ perspectives first-hand and consider things that I wouldn’t have thought about on my own,” he said. “It makes me a more well-rounded researcher.”
As Chris nears graduation, he prepares his research for the next cohort of graduate students to continue. “Science is a marathon, not a sprint, and is met with a lot of ‘brick walls’ and frustration,” said Chris. “Having patience, taking a step back, and looking at it from different perspectives [makes it possible to] change the world one small victory at a time. The experiments won’t always work, but that’s the point of research.”
Praise for Chris
Dr. Grayson praised how Chris tested the team’s theory that silica nanoparticles modified with surfactant polymers could successfully stabilize oil mixtures in water. He explained that Chris’s experiments built upon previous research to include more oil dispersion processes and remove high temperatures associated with synthesizing the polymers and nanoparticles. “Chris has done a great job working on this theory,” said Dr. Grayson. “It appears in these last few months that he will finally achieve everything that we had hoped for: an environmentally friendly, non-toxic oil dispersant.”
The GoMRI community embraces bright and dedicated students like Chris Keller and their important contributions. The GoMRI Scholars Program recognizes graduate students whose work focuses on GoMRI-funded projects and builds community for the next generation of ocean science professionals.
By Stephanie Ellis and Nilde Maggie Dannreuther. Contact sellis@ngi.msstate.edu for questions or comments.
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The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.
© Copyright 2010-2019 Gulf of Mexico Research Initiative (GoMRI) – All Rights Reserved. Redistribution is encouraged with acknowledgement to the Gulf of Mexico Research Initiative (GoMRI). Please credit images and/or videos as done in each article. Questions? Contact web-content editor Nilde “Maggie” Dannreuther, Northern Gulf Institute, Mississippi State University (maggied@ngi.msstate.edu).
The Sea Grant Oil Spill Outreach Team released a product that concisely summarizes recent science regarding how dispersants work, how they are used, and how they affect sea life. The fact sheet also includes information on existing policies for chemical dispersants and how dispersants were used during Deepwater Horizon.
Read Frequently Asked Questions: Dispersant Edition and learn about dispersant-related research and how scientists are investigating how laboratory-based results relate to the ever-changing conditions in nature.
By Nilde Maggie Dannreuther. Contact maggied@ngi.msstate.edu with questions or comments.
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The Sea Grant Oil Spill Outreach Team synthesizes peer-reviewed science for a broad range of general audiences, particularly those who live and work across the Gulf Coast. Sea Grant offers oil-spill related public seminars across the United States.
Information about upcoming Sea Grant science seminars and recently-held events is available here. To receive email updates about seminars, publications, and the outreach team, click here.
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GoMRI and the Sea Grant programs of the Gulf of Mexico (Florida, Mississippi-Alabama, Louisiana, and Texas) have partnered to create an oil spill science outreach program.
The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit https://gulfresearchinitiative.org/.
© Copyright 2010- 2019 Gulf of Mexico Research Initiative (GoMRI) – All Rights Reserved. Redistribution is encouraged with acknowledgement to the Gulf of Mexico Research Initiative (GoMRI). Please credit images and/or videos as done in each article. Questions? Contact web-content editor Nilde “Maggie” Dannreuther, Northern Gulf Institute, Mississippi State University (maggied@ngi.msstate.edu).
David uses mesocosms to simulate conditions in the natural ocean environment. (Photo credit: ADDOMEx)
Crude oil contains tens of thousands of hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs) that create unique chemical fingerprints for different types of oil. Dawei “David” Shi uses geochemical analysis techniques in mesocosm studies to track these fingerprints, observe how they change over time, and investigate how dispersant affects PAH concentrations in the water column.
David is a Ph.D. student with Texas A&M University’s Department of Oceanography, a researcher with the Geochemical and Environmental Research Group (GERG), and a GoMRI Scholar with the Aggregation and Degradation of Dispersants and Oil by Microbial Exopolymers (ADDOMEx) consortium.
His Path
David’s parents encouraged his early interest in science as a child growing up in southern China where his father was a physical oceanography professor. He became interested in environmental science after visiting coastal cities as a middle school and high school student. These cities were located in the fastest-developing region of China, and the local environment suffered as a result.
David attended the Hong Kong University of Science and Technology where he completed a bachelor’s degree in chemistry and a master’s degree in environmental science. David’s application to Texas A&M University’s oceanography Ph.D. program caught the attention of Dr. Terry Wade, who thought that David’s scientific background would be perfect for his research investigating microbes’ role in oil sedimentation and degradation. Shortly afterwards, David began his Ph.D. work as a member of Wade’s lab.
His Work
While oil contains many hydrocarbons, only PAHs produce a strong fluorescent signature. PAHs typically represent a relatively fixed percentage of total petroleum hydrocarbons, allowing researchers to estimate the concentration of dissolved oil in a water sample based on its PAH concentrations. This measurement is called an estimated oil equivalent (EOE).
David takes fluorescence measurements to identify the presence of PAHs in his samples. (Provided by David Shi)
David investigates the role of microbes in oil sedimentation and degradation using mesocosm experiments to simulate the ocean environment. The ADDOMEx team prepares water-accommodated fractions (WAFs) and chemically enhanced WAFs (CEWAFs) by adding Macondo surrogate oil or surrogate oil plus Corexit 9500 (1:20 ratio, consistent with EPA recommendations) to seawater and filling twelve 120 L mesocosm tanks with these mixtures. The EOE in the mesocosms is 0.2-0.7 mg/L or ppm for WAF treatments and 39-81 mg/L or ppm for CEWAF treatments.
Then the team adds microbes collected with a plankton net from Galveston Bay and the Flower Garden Banks National Marine Sanctuary (an open ocean site in the Gulf of Mexico) to the mesocosm tanks. They collect water samples at the beginning of the experiment and every 24 hours for 72 – 96 hours thereafter and determines the EOE using total scanning fluorescence, an analytical technique that can selectively screen samples for PAH presence.
“It only takes approximately five minutes to process a sample using this technique, and it provides an approach to quickly determine the oil concentration in situ,” said David. “The main drawback of the fluorescence technique is that it provides few details about the composition of these PAHs, because their fluorescence signatures are very similar.”
David uses gas chromatography-mass spectrometry to fill in the missing information about the PAH compositions in the samples. His early results showed that low molecular weight (LMW) and high molecular weight (HMW) PAH concentrations reduced at about the same rate when dispersants were present. In trials without dispersants, LMW-PAHs vanished in about one day while HMW-PAHs persisted longer, with some compounds barely diminishing after four days. David said that this observation is important because HMW-PAH compounds are more carcinogenic than LMW-PAHs.
David believes that his preliminary results suggest that dispersant may alter the removal of PAH compounds from the water column, and he is working to characterize the nature of those alterations. He plans to conduct more mesocosm experiments that focus on the entry and removal of PAHs from sediments. “Hopefully, we will find out how much of these PAHs get into sediment and how much is biodegraded in situ,” he said. “Whether dispersants enhance oil biodegradation is still not clear, but it is an important issue and I hope my research can contribute to our understanding of it.”
His Learning
David’s research experiences have shown him the importance of cross-field training to an environmental science career. Because he analyzes data primarily from a chemistry perspective, he felt “enlightened” when he heard other researchers discuss the results in a biological context. He has enjoyed the poster sessions during Gulf of Mexico Oil Spill and Ecosystem Science conferences because presenters provided insights into his work. “People from different scientific backgrounds walked by and discussed my poster with me,” he explained. “Not only did I enjoy making connections to fellow scientists, sometimes the discussion itself was really inspiring and encouraged me to think outside the box.”
David (back row, far left) and the ADDOMEx research team in June 2016. (Provided by David Shi)
His Future
David plans to pursue a post-doc position in China followed by an academic or industry career that would allow him to use his education and expertise to improve China’s environmental conditions. He advises students considering a scientific career to engage in a wide range of sciences, “One should have a very broad understanding of all natural science fields, rather than simply focusing on one’s own discipline.”
The GoMRI community embraces bright and dedicated students like David Shi and their important contributions. The GoMRI Scholars Program recognizes graduate students whose work focuses on GoMRI-funded projects and builds community for the next generation of ocean science professionals. Visit the ADDOMEx website to learn more about their work.
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The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.
© Copyright 2010- 2017 Gulf of Mexico Research Initiative (GoMRI) – All Rights Reserved. Redistribution is encouraged with acknowledgement to the Gulf of Mexico Research Initiative (GoMRI). Please credit images and/or videos as done in each article. Questions? Contact web-content editor Nilde “Maggie” Dannreuther, Northern Gulf Institute, Mississippi State University (maggied@ngi.msstate.edu).
The Molecular Engineering of Food-Grade Dispersants as Highly Efficient and Safe Materials for the Treatment of Oil Spills project is lead by P.I. Srinivasa R. Raghavan, University of Maryland
The goal is to engineer a new class of dispersants that combine environmental safety and high efficiency. By avoiding the synthetic components in current dispersants that are of questionable toxicity, and replacing them with food-grade components, new dispersants will be created that are nontoxic and safe for use in aquatic environments. At the same time, through an improved understanding of the fundamentals of dispersion, high dispersion efficiencies will be achieved that are comparable or higher than with current dispersants i.e., the Corexits.
The use of food-grade dispersants will enable a safer and more environment-friendly approach to the mitigation of crude oil spills, which will help avert issues of public concern regarding dispersant toxicity. Molecular-level insights into dispersant action via innovative experiments will reveal ways to enhance the efficiency of dispersion and also allow for dispersants to be optimized for a variety of complex conditions (such as dispersion of highly viscous or weathered oils).
The project will involve the following five approaches: (1) Optimizing Food-Grade Surfactant Mixtures; (2) Optimizing Solvents and the Overall Dispersant; (3) Optimize Dispersants for Different Conditions (Oil, Water, Temperature); (4) Pilot-Scale Testing; and (5) Biodegradation and Toxicity Testing.
The concept of food-grade dispersants is one of the truly promising ideas to come out of the work done under C-MEDS. This project seeks to translate the inherent idea into a practical and viable technology. Towards this end, pilot-scale testing of optimized food-grade dispersants (Approach 4) will be conducted using the indoor wave tanks at S. L. Ross Environmental Research. In addition, initial tests on bacterial biodegradation in the presence of food-grade dispersants will be studied (Approach 5). The toxicity of these dispersants to aquatic species will also be studied using commercial assays, and further aspects concerning toxicity and biological effects will be investigated together with collaborators.
Click for access to GoMRI’s YouTube videos of RFP-V Projects…
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This project was funded by the Gulf of Mexico Research Initiative (GoMRI) in the RFP-V funding program.
The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.
Cover of the September 2016 Oceanography Magazine, Volume 29, Number 3
7th year of the largest coordinated research endeavor around an ocean event.
The 2010 Deepwater Horizon oil spill and subsequent response efforts raised concerns about impacts on the Gulf of Mexico’s ocean and coastal environments. The Gulf of Mexico Research Initiative (GoMRI), in response to the spill, initiated an unprecedented 10-year scientific research program funded by BP. Seven years into the program, we know more than ever before about the Gulf’s complex environment, dynamic processes, and response to stressors.
Oceanography magazine dedicated a special issue to this research, GoMRI: Deepwater Horizon Oil Spill and Ecosystem Science, and below are highlights from 13 papers it featured.*
WHERE OIL WENT
Surface oil covered a cumulative area of 149,000 km2 in the northeastern Gulf. Wind and currents transported surface slicks towards land, affecting approximately 1,800-2,100 km of shoreline, a third of which were moderately to heavily oiled including 1,075 km in Louisiana. Macondo oil was visually evident at the edge of Louisiana marshes and up to 10 m inland.
Subsea oil and gas rose through the water column and formed an underwater oil plume that covered an area of approximately 930 km2 and made direct contact with continental slope sediments. A significant proportion of surface oil returned to the deep seafloor primarily through an extensive marine oil snow sedimentation event known as a “dirty blizzard,” forming a 0.5-1.2 cm thick floc layer.
Cleanup efforts removed oil from 73% of beaches affected by the spill, but residual oil remained as surface residue balls (SRBs), submerged oil mats, and in marsh plants and sediment, and is subject to continued weathering, biodegradation, and possible resuspension.
HOW OIL CHANGED
Crude oils contain thousands of compounds that, upon entering a marine environment, undergo significant compositional changes from weathering processes such as evaporation, dissolution, emulsification, dispersion, sedimentation/flocculation, microbial degradation, and photooxidation.
Most crude oil compounds are readily biodegradable and generally follow a clear degradation pattern: n-alkanes first followed by branched alkanes, lower molecular weight aromatics, higher molecular weight aromatics, and cyclic alkanes. Anaerobic biodegradation is a slower process than aerobic degradation, and crude oil compounds can remain relatively unaltered in reduced sediments and environments for long time periods and may appear as relatively fresh oil compared to surface oil exposed to aerobic conditions.
MICROBIAL RESPONSE AFFECTING OIL FATE
Macondo oil had a relatively low content of persistent resins and asphaltenes, and warm temperatures supported geochemical and biological degradation. The prevalence of oil-degrading bacteria generated a prompt response from the microbial community and subsequent biodegradation. Microbial communities in the plume were different from those in non-plume waters and exhibited a significant enrichment of hydrocarbon-degrading metabolic genes. Aerobic oxidation of short chain alkanes, propane, and butane caused up to 70% of oxygen depletion observed in the oil plume.
Residual oil trapped in Pensacola Beach sands showed a progression of microbial populations linked to hydrocarbon degradation. Early-responder microbes were followed by populations capable of aromatic hydrocarbon decomposition. Microbial abundance in oiled sands was 10-10,000 times that in clean sands in the first four months after oil came ashore. A typical beach-environment microbial community returned after one year but differed significantly from pre-spill communities.
DEEP OCEAN IMPACTS
Carbon from the spill was likely incorporated into the mesopelagic (200-1,000 m depth) food web through consumption of prey rich in depleted carbon. The nature of microbial communities in the deep sea likely changed. An 80-93% decline in benthic foraminifera was related to reducing conditions and increased polycyclic aromatic hydrocarbons (PAH) concentrations.
Deepsea megafauna had lower diversity and abundance near the spill site relative to regions farther away, though blue marlin, Atlantic sailfish, blackfin tuna, and dolphinfish showed no significant reduction in larval abundance. Bottom-dwelling golden tilefish had the highest concentrations of naphthalene metabolite levels in bile measured in fishes globally. Tunas and jacks collected near the spill site exhibited developmental crude oil cardiotoxicity, suggesting a possible loss of early predator recruits that spawn in open waters. Sperm whale acoustic activity decreased near the spill site by a factor of two and increased farther away, suggesting they relocated.
Hard-bottom communities, including natural and artificial reefs, suffered injuries that were severe and long-lasting. Macrofauna and meiofauna diversity had not recovered after four years, and community structure differences still persist. Deep-sea colonial corals, in particular octocorals near the spill site, showed visible evidence of impact, and flocculent material covering the coral contained chemical fingerprints associated with Macondo oil and DOSS (dioctyl sodium sulfosuccinate). Researchers returned to these coral eight times and observed continued impacts such as tissue death with some coral skeletons secondarily colonized by hydrozoans.
Field measurements showed that planktonic community abundance and species composition returned to pre-spill conditions within a year. Laboratory experiments indicated that zooplankton exposed to sublethal crude oil levels bioaccumulated five PAHs, which could increase their susceptibility to predation and enhance trophic transfer of toxic PAHs.
MARSH IMPACTS
There were immediate negative impacts in moderately to heavily oiled marshes in southeastern Louisiana. The average concentration of total alkanes and PAHs in June 2013 was 20 and 374 times pre-oiled conditions, respectively. Total alkane concentrations were on a trajectory to be near baseline levels by 2015, but this did not occur likely a result of multiple resuspension events from storms.
Some damaged marsh shorelines showed precipitous shoreline erosion at least 2.5 years after oiling due to damaged root systems. Marshes lost due to oiling and shoreline erosion will not return without human intervention. Forty-two months after the spill, heavily oiled marshes showed near-complete plant mortality, and live aboveground biomass was 50% of reference marshes. Decreased living marsh vegetation and population levels of some fauna were obvious for 2-5 years. Meiofauna density was lower along with S. alterniflora grasses in heavily oiled areas.
Fiddler crab average size declined and there were proportion shifts in two species composition. Periwinkle snails density declined, and a slow recovery in abundance and size distribution was related to habitat recovery. Worms, seed shrimp, and mud dragons had not recovered to background levels 48 months post-spill. Killifish showed little evidence of spill impacts. Horse fly abundance declined sharply. Arthropods were suppressed by 50% in 2010 but had largely recovered in 2011. Seaside Sparrow nests on unoiled sites were more likely to fledge than those on oiled sites. Loons varied in frequency with PAHs by year and exhibited reduced body mass as PAH concentrations increased.
These effects are expected to continue – possibly for decades – to some degree, or the marsh ecosystem will reach a new baseline condition in heavily damaged areas.
FISH & SEAFOOD IMPACTS
Commercial, recreational, and subsistence fisheries were closed in fall 2010 in areas where oil was observed and predicted to travel and reopened by April 2011. Impacts on fisheries productivity were relatively short-lived, with landings and their values returning to pre-spill levels or greater for most fishery species. However, long-term effects are yet to be determined. Laboratory studies indicate that early life stages of fish are generally more sensitive to oil and dispersant’s sublethal effects (with some resulting in reduced swimming performance and cardiac function) than adults.
Public health risks from exposure to crude oil residue through seafood or coastal beaches returned to pre-spill levels after the spill dissipated. Seafood from reopened areas was found to be safe for consumption, with PAH levels comparable to those found in common local processed foods. PAH concentrations detected in many seafood samples during and following the spill were at least 2 orders of magnitude below levels of public health concern. DOSS was detected in less than 1% of samples and at levels below public health concern.
Tests on SRBs showed that Vibrio vulnificus were 10 times higher than the surrounding sand and up to 100 times higher than seawater, suggesting that SRBs can act as reservoirs for bacteria including human pathogens. Coquina clams initially showed higher PAH levels relative to the surrounding sand, but levels decreased continuously and were undetectable in sand (one year) and Coquina tissues (two years).
DISPERSANT EFFECTS & FUTURE TECHNOLOGIES
Dispersant increased the oil fraction that spread within the water column and laterally displaced oil that reached the sea surface. Dispersants reduced droplet sizes and rise velocities, resulting in a more than tenfold increase in the downstream length of the surface oil footprint.
Chemical dispersants may be more toxic to some marine organisms than previously thought, and small oil droplets created by dispersant use and directly consumed by marine organisms are often more toxic than crude oil alone. Dispersant effects on microorganisms might be taxa-specific, and some studies suggest that dispersants stimulated biodegradation while others conclude the opposite. Degradation rates of hexadecane and naphthalene were more rapid in the absence of dispersants, as was the overall removal of the water-accommodated oil fraction.
Dispersant applied at the broken riser pipe helped form a deep water oil plume. DOSS was likely transferred to the plume and was later detected in surface sediments, on corals, and within oil-sand patties.
A future option is development of plant-based materials for efficient chemical herding of compact oil slicks into layers that are sufficiently thick to enable oil burning or skimming. Opportunities exist for new dispersants that work in synergy with current dispersants and mitigate some of their disadvantages. Examples include a system containing soybean lecithin and the surfactant Tween 80, substitution of lecithin for DOSS, and using carbon-based particles and silicas to stabilize emulsified droplets. Laboratory research needs to be conducted at concentrations and under conditions relevant to marine environments.
MODELING CAPABILITIES
Model improvements provide a better understanding of droplet formation in the turbulent plume above the wellhead. No model during the spill could predict droplet size distribution, which dictates rise times, dissolution, and biodegradation. Oil spill models now include the ability to simulate the rise of a buoyant oil plume from the seabed to the surface. Consideration of oil’s 3D movement permits the prediction of oil spreading through subsurface plumes. Our understanding of the near-surface oceanic layer and atmospheric boundary layer, including the influences of waves and wind, has also improved.
Oil spill modeling routines will likely be included in Earth system models, linking physical models with marine sediment and biogeochemical components. Advances in coupled nearfield-farfield dynamic modeling together with real-time, seven-day circulation forecasts allow for near-real-time tracking and forecasting of oil dynamics. This is the most promising approach for rapid evaluation of blowout predictions to support first response decisions.
* Overton, E.B., T.L. Wade, J.R. Radović, B.M. Meyer, M.S. Miles, and S.R. Larter. 2016. Chemical composition of Macondo and other crude oils and compositional alterations during oil spills. Oceanography 29(3):50–63
Socolofsky, S.A., E.E. Adams, C.B. Paris, and D. Yang. 2016. How do oil, gas, and water interact near a subsea blowout? Oceanography 29(3):64–75
Passow, U., and R.D. Hetland. 2016. What happened to all of the oil? Oceanography 29(3):88–95
Özgökmen, T.M., E.P. Chassignet, C.N. Dawson, D. Dukhovskoy, G. Jacobs, J. Ledwell, O. Garcia-Pineda, I.R. MacDonald, S.L. Morey, M.J. Olascoaga, A.C. Poje, M. Reed, and J. Skancke. 2016. Over what area did the oil and gas spread during the 2010 Deepwater Horizon oil spill? Oceanography 29(3):96–107
John, V., C. Arnosti, J. Field, E. Kujawinski, and A. McCormick. 2016. The role of dispersants in oil spill remediation: Fundamental concepts, rationale for use, fate, and transport issues. Oceanography 29(3):108–117
Passow, U., and K. Ziervogel. 2016. Marine snow sedimented oil released during the Deepwater Horizon spill. Oceanography 29(3):118–125
Tarr, M.A., P. Zito, E.B. Overton, G.M. Olson, P.L. Adhikari, and C.M. Reddy. 2016. Weathering of oil spilled in the marine environment. Oceanography 29(3):126–135
Joye, S.B., S. Kleindienst, J.A. Gilbert, K.M. Handley, P. Weisenhorn, W.A. Overholt, and J.E. Kostka. 2016. Responses of microbial communities to hydrocarbon exposures. Oceanography 29(3):136–149
Rabalais, N.N., and R.E. Turner. 2016. Effects of the Deepwater Horizon oil spill on coastal marshes and associated organisms. Oceanography 29(3):150–159
Murawski, S.A., J.W. Fleeger, W.F. Patterson III, C. Hu, K. Daly, I. Romero, and G.A. Toro-Farmer. 2016. How did the Deepwater Horizon oil spill affect coastal and continental shelf ecosystems of the Gulf of Mexico? Oceanography 29(3):160–173
Buskey, E.J., H.K. White, and A.J. Esbaugh. 2016. Impact of oil spills on marine life in the Gulf of Mexico: Effects on plankton, nekton, and deep-sea benthos. Oceanography 29(3):174–181
Fisher, C.R., P.A. Montagna, and T.T. Sutton. 2016. How did the Deepwater Horizon oil spill impact deep-sea ecosystems? Oceanography 29(3):182–195
Dickey, R., and M. Huettel. 2016. Seafood and beach safety in the aftermath of the Deepwater Horizon oil spill. Oceanography 29(3):196–203
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The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.
© Copyright 2010- 2017 Gulf of Mexico Research Initiative (GoMRI) – All Rights Reserved. Redistribution is encouraged with acknowledgement to the Gulf of Mexico Research Initiative (GoMRI). Please credit images and/or videos as done in each article. Questions? Contact web-content editor Nilde “Maggie” Dannreuther, Northern Gulf Institute, Mississippi State University (maggied@ngi.msstate.edu).
The Design of Synergistic Dispersant and Herding Systems using Tubular Clay Structures and Gel Phase Materials project is lead by P.I. Vijay John, Tulane University.
Dispersants are typically solutions containing one or more surfactants dissolved in a solvent. They work by reducing the interfacial tension between oil and water, thereby reducing the work needed to break oil into sufficiently small droplets that are in the colloidal size range and disperse into the water column. The COREXIT class of dispersants (C9500) was used extensively in the Deepwater Horizon incident, and was considered a success in preventing significant amounts of oil from reaching the shoreline. The ecological consequences of deep sea dispersant addition and subsequent oil dispersion are issues of intensive research efforts.
From a technological perspective, there are significant opportunities to improve dispersant efficiency. C9500 and other commercial dispersants are not effective in the dispersion of weathered oil and high viscosity crudes. Some components of C9500, in particular the di-octyl sodium sulfosuccinate (DOSS) component, may persist for extended periods in the marine environment. C9500 also contains a significant amount of paraffin as solvent, and alternative formulations that decrease the solvent content while maintaining efficiency are desirable. Being a liquid solution, significant amounts of dispersant become wasted if encounter with oil is not rapidly realized.
It is therefore proposed to conduct fundamental and applied research to develop dispersant systems that are synergistic with C9500, but that may alleviate many of the disadvantages of C9500 without the need for entirely different chemical components. This is motivated by the realization that many years of research have gone into the development of C9500 which is currently stockpiled along coastlines of offshore oil exploration and production. The proposed research involves fundamental concepts relevant to the stabilization oil droplets by particles (Pickering emulsions) that are relevant to the formation of oilmineral aggregates. While such particles stabilize oil droplets against coalescence, they do not lead to the generation of small droplets which require the surfactants in dispersants to significantly reduce the oil-water interfacial tension. The innovation in the proposed work lies in the use of natural tubular clays known as halloysites which are available in the large quantities necessary for oil spill remediation. When filled with surfactant, the clays not only stabilize the oil drops against coalescence, but also reduce the interfacial tension through a targeted release of surfactant to the oil-water interface. This is Specific Aim 1 of the proposal. Concomitantly, it is proposed to develop a new gel based dispersant that adheres to the oil and is buoyant, thus encountering oil efficiently, and has the potential to disperse weathered oil. The encapsulation of these gels into the tubular lumen of halloysite and the targeted delivery to oil are the topics of Specific Aim 2.
It is also the hypothesis that the presence of a solid phase (halloysite clay tubes) at the oil-water interface will facilitate anchoring of microbial oil degrading communities to the interface and will enhance biodegradation. Specific aim 3 therefore, is to examine the microbial degradation of oil when the interface is stabilized by halloysite. Our innovation lies in the understanding of microbial biodegradation by following the process at the nanoscale using high resolution cryogenic electron microscopy to characterize biofilm formation and the dynamics of oil droplet degradation. It is also the objective that such studies will provide insights into the formation of marine snow.
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This project was funded by the Gulf of Mexico Research Initiative (GoMRI) in the RFP-V funding program.
The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.
This figure depicts two vials in which a thin layer of crude oil was placed over simulated sea water. Different dispersants were added to each vial, and the vials were lightly shaken and photographed 30 minutes later. The left vial shows an example of bad or ineffective emulsion, where the crude oil remains as a dark brown slick on the water’s surface and the water column contains negligible oil. The right vial shows an example of good and effective emulsion, where the crude oil is dispersed into small droplets in the water column. (Photos by Jasmin Athas)
Oil spill responders currently have the option to treat oil spills with a synthetic dispersant called Corexit, however scientists continue to search for alternatives. In this search, scientists seek to develop an understanding of the specific mechanisms that drive dispersion and identify an effective combination of food-grade components.
The Gulf of Mexico Research Initiative (GoMRI) awarded Dr. Srinivasa Raghavan a grant to investigate and identify a viable alternative to Corexit. Dispersants contain surfactant compounds that help break up oil into tiny droplets, particularly when the oil encounters agitations such as wave motion. Preliminary research identified soy lecithin, a nontoxic food-grade surfactant, as a viable replacement for dioctyl sodium sulfosuccinate (DOSS), a synthetic surfactant that is one of Corexit’s major oil-dispersing compounds.
The team will study the fundamental mechanisms of efficient dispersion to reveal ways that dispersant formulations can be enhanced and optimized for a variety of complex applications, such as dispersing highly viscous or weathered oils. The researchers will apply various combinations of lecithin and other widely available food-grade surfactants to a thin oil layer on a simulated saltwater sea surface and identify which formulations best disperse oil. They will examine how much oil is dispersed and the dispersed oil’s stability to remain in the water column and not recoalesce at the surface.
Once the team identifies the most effective formulations, they will investigate the factors that contribute to effective dispersion. This process will include assessing the mechanisms behind oil dispersion and the way those mechanisms differ from emulsification (the stable suspension of oil droplets in water when mixed vigorously). The researchers hypothesize that a dispersant’s effectiveness is heavily influenced by its molecular nanostructure. “That is the true mystery aspect of this research – why are some formulations better than others?” said Raghavan. “We are finding that in the current literature there is no good answer to this question.”
The team hopes their findings will influence future dispersant design towards more effective and environmentally benign formulations. Raghavan commented, “We’ve set out to find an effective, nontoxic formulation that we can clearly prove is better than the current standard. Our hope is that our data and findings will be eye-opening and generate an incentive for change.”
The project’s researchers are Srinivasa Raghavan at the University of Maryland Department of Chemical and Biomolecular Engineering, Geoffrey Bothun at the University of Rhode Island Department of Chemical Engineering,Vijay John at the Tulane University Department of Chemical and Biomolecular Engineering, and Alon McCormick at the University of Minnesota Department of Chemical Engineering and Materials Science. Their project is Molecular Engineering of Food-Grade Dispersants as Highly Efficient and Safe Materials for the Treatment of Oil Spills.
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The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.
David Podgorski uses a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer at the National High Magnetic Field Laboratory to analyze weathered oil samples and changes to their molecular structure. (Photo by Kristen Coyne)
Responders to the Deepwater Horizon spill used large quantities of dispersant to facilitate oil biodegradation, but could a different method be safer for the environment?
Oil compounds take on additional oxygen atoms as physical and chemical processes weather them. However, the classical methods that scientists use to analyze and describe these molecular compositional changes cannot detect the new oxidized products, limiting our understanding of their molecular structure, environmental fate, and potential toxicity.
The Gulf of Mexico Research Initiative awarded Dr. Ryan Rodgers a grant to investigate these products, the processes that yield them, and their potential toxicity using classical and new techniques. Rodgers and co-principle investigators Chris Reddy and Christoph Aeppli will use their findings to create a model that will help determine the rate, mass, and type of weathering products of future spills.
Christoph Aeppli labels oil samples collected from Alabama beaches. Chemical analysis of these samples will determine the degree of natural oil degradation that occurred since the Deepwater Horizon spill. (Photo by Christopher Reddy)
The team will use gas chromatography methods to analyze oil samples collected immediately after and in the years following the spill, identifying their chemical “fingerprints,” determining their origin, and characterizing changes to their molecular structure.
Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICRMS) – an analytical technique with significantly higher resolution than classical methods – will help researchers track molecular-level changes in the oxidized transformation products created during weathering.
The researchers will investigate how structure affects weathering by separating unweathered oil components into saturates (waxy oil compounds) and one to five+ ringed aromatics (hydrocarbons containing ring-shaped carbon structures) and then irradiating the compounds using simulated sunlight or incubating them in a dark mesocosm containing oil-degrading bacteria. The team will screen the resulting transformation products’ toxicity to determine the most and least harmful compounds.
Chris Reddy collects oil samples on Alabama beaches. These sand-oil aggregates continue to wash ashore six years after the Deepwater Horizon oil spill. (Photo by Christoph Aeppli)
The combined degradation and toxicity data will reveal whether the individual saturates and aromatic fractions release more or less toxic transformation products in response to biodegradation or photo-oxidation.
The researchers hope that responders to future spills can use this study’s model to examine oil compounds and inform remediation decisions based on degradation processes that yield less toxic transformation products.
Rodgers gave the example that, if biodegradation would release highly toxic compounds from a certain oil type, responders may decide to let surface oil be photo-oxidized or burned. Alternatively, if photo-oxidation would lead to toxic compounds, responders may choose to use dispersants to facilitate biodegradation.
Huan Chen tests the toxicity of photo-irradiated samples to identify which original crude oil components become more toxic with weathering. (Photo by Phoebe Z. Ray)
“We didn’t have the technology to do this kind of research ten or fifteen years ago,” said Rodgers. “Now, we can collect massive amounts of information about petroleum’s structural classes and how photo-oxidation and biodegradation make them more or less toxic. This information gives us as a community the best shot to understand how spilled petroleum will behave in the environment and will be immensely informative moving forward.”
The project’s researchers are Ryan Rodgers of Florida State University, Chris Reddy of Woods Hole Oceanographic Institution, andChristoph Aeppli of Bigelow Laboratory for Ocean Sciences. Their project is The State-of-the-Art Unraveling of the Biotic and Abiotic Chemical Evolution of Macondo Oil: 2010-2018.
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Phoebe Ray works on a solar simulator at the National High Magnetic Field Laboratory, which will generate photo-oxidized oil samples for subsequent analysis. (Photo by Stephen Bilenky)
The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visithttp://gulfresearchinitiative.org/.
(Click image to enlarge and for more info)
Research about commercial dispersant safety has seen increased efforts to identify benign alternatives and improve current dispersant systems since the Deepwater Horizon oil spill.
Preliminary research suggests that dispersants formulated as gels may be a viable alternative to liquid dispersants and may address certain problems and concerns about Corexit 9500 use and application.
The Gulf of Mexico Research Initiative recently awarded Dr. Vijay John a grant to pursue the development of a surfactant gel dispersant and expand research that he and colleagues conducted about halloysite clay nanotubes as a dispersant delivery system.
John’s team believes that these biodegradable materials could have applications as safe technologies for chemical herding, a process that uses surfactants at the air-water interface to form oil layers thick enough to be burned or skimmed.
(Click image to enlarge and for more info)
John and his team are developing a gel formulation that contains all but two Corexit 9500 components – Span 80 and the solvent propylene glycol – and replaces a significant amount of the potentially harmful surfactant DOSS with lecithin, a food-grade emulsifier.
Surfactants help break up oil by lowering the surface tension at the oil-water interface, and early tests have shown that this new gel formulation reduces surface tension as successfully as Corexit. The team will investigate the physical characteristics of gel-created dispersions and assess the gel’s effect on oil degradation compared to Corexit.
The researchers will then examine if the clay nanotubes could be used to deliver the gel to an oil-water interface, similar to a surface oil slick. Problems with traditional liquid dispersants most often arise during and after their delivery to the ocean surface.
The gel has a crystalline mesoscale structure that ranges from hexagonal to sheet-like and onion-like multilamellar structures. (Images by Olasehinde Owoseni)
Responders apply liquid dispersants as a mist, but it tends to roll off of weathered surface oil and is often washed away before oil can be mitigated. However, nanotubes and naturally buoyant gel dispersants stick to the weathered oil and allow a more direct application of dispersant to an oil spill.
“It’s like a targeted drug delivery system,” explained John. “If you want to deliver drugs to only a tumor and not healthy organs, you have to contain them in something that will target the tumor. We’re trying to do the equivalent in the marine environment using naturally buoyant gel and dispersant-filled nanotubes to target the oil-water interface.”
Vijay John (pictured) and his team are investigating safer, more efficient alternatives to current methods of oil dispersal. (Provided by Paula Burch-Celentano/Tulane University)
The project’s researchers are Vijay John and Diane Blake of Tulane University and Yuri M. Lvov and Donghui Zhang of Louisiana State University. Their project is The Design of Synergistic Dispersant and Herding Systems using Tubular Clay Structures and Gel Phase Materials.
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The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.
Bryan traveled to a Florida Strait sampling site to collect bacteria. He analyzed these samples to identify differences between microbial communities in the sea surface microlayer and underlying subsurface water. (Photo credit: Alexander Soloviev)
Bryan Hamilton never planned to be a microbiologist, but when the opportunity arose to study microbes that produce biosurfactant in response to oil exposure, he was drawn in completely. His research investigated the potential connection between these microbes and natural surface slicks and if this connection could help scientists detect oil below the water’s surface.
Bryan completed a marine biology masters’ degree at Nova Southeastern University while he was a GoMRI Scholar with CARTHE. He shared the research experiences that altered the path of his scientific career.
His Path
Bryan first saw the ocean when he was six years old during a family trip to the East Coast and became fascinated with the marine life he encountered. He realized then that he wanted to work in the marine environment when he grew up. After high school, he attended the Palm Beach Atlantic University to study marine biology.
Bryan credits his involvement with GoMRI research to Dr. Alexandre Soloviev who had a graduate student position available studying marine bacteria in his physical oceanography lab at Nova Southeastern University. Bryan was initially unsure of his interest in studying bacteria (he felt more like a shark guy), but was hooked when he learned he would be investigating sea-surface bacteria’s role in slick formation. “The research sounded like something I would love to be a part of,” he said. “That project was part of CARTHE and introduced me to many of the researchers I work with today.”
His Work
Bryan prepares a polymerase chain reaction to determine bacterial abundance in sea surface microlayer samples taken from the Florida Strait and Gulf of Mexico. (Photo credit: Cayla Dean)
Bryan explained that although the word “slick” is often associated with oil spills, these films on the water’s surface can occur for many reasons, including the accumulation of surfactants. Surfactants are compounds that help break up oil in the water column, resulting in smaller oil droplets. “Sea slicks formed by biosurfactants could serve as an indicator of the presence of organic matter in the water column,” he explained. “Surfactants travel to the surface, so it might be possible to determine if there is oil in the water column based on satellite images of natural surfactant slick formations.”
Bryan’s research focused on surfactant-producing bacteria living in or near the sea-surface microlayer (the upper 1 mm of the ocean where air meets sea). His team used Synthetic Aperture Radar (SAR) satellite imagery to identify slicks across the Gulf of Mexico and Florida Straight. He then conducted DNA analysis on bacteria collected from these areas to detect differences in the abundance of surfactant-producing bacteria under slick and non-slick conditions. His observations appear to support a microbe-slick connection, as there was a higher abundance of these bacteria in slick areas compared to non-slick areas.
Bryan believes that learning more about the microbes that are active in the air-sea interface will help researchers better understand sea-surface oil transport. “Bacteria are so important to the ocean ecosystem,” he said. “The potential links between microbial life and surface features seen in satellite images may help improve recovery efforts and strategies.”
His Learning
Bryan called his work with Soloviev his “first real taste of research” that prepared him for the scientific field. The trial-and-error process of designing more efficient sampling techniques was at first frustrating, but he and Soloviev were able to make improvements as they continued. “I learned that there is a lot more to research than conducting an experiment and seeing what you find,” said Bryan. “There are often many attempts and failures before you figure out the best way to do something.”
Through his work with CARTHE, Bryan discovered how eager other scientists were to collaborate. His most memorable experience was participating in CARTHE’s Surfzone Coastal Oil Pathways Experiment (SCOPE), which used drifters, dye, and drones to research the mechanisms that move water-borne materials onshore. During the event, everyone’s willingness to help with each other’s experiments impressed Bryan, “It was quite a large group of people, so teamwork was extremely important to the experiment’s success. It was great to see everyone working together to solve a problem.”
His Future
Bryan recently completed his masters’ degree and accepted a molecular biologist position near Miami, but remains open to the possibility of pursuing a Ph.D. He said that the lab work involved in his CARTHE research gave him the necessary experience for the job. “My GoMRI experience really opened up my options for a career after graduate school, especially since genetic work can be applied to wide range of fields.”
Bryan suggested that future science students should get involved in as many activities and volunteer opportunities that they can, even if the work is outside of their direct interests. He explained that getting involved with other researchers can open up new opportunities and lead to connections with people in your area of interest. “You never know who you will meet or what you will learn through those experiences,” he said.
Praise for Bryan
Soloviev described Bryan as a “bright, hard-working young researcher who goes above and beyond to understand complex biophysical problems.” He praised Bryan’s contributions to the development of a microlayer sampling technique that reduces interference from the research ship, ship wake, and researcher activities. The improved technique was implemented during the SCOPE program and made sample collection more efficient and possible across a wider range of wind-wave conditions, resulting in more samples being collected, improving the project’s statistics.
Soloviev also noted Bryan’s other accomplishments, including oral presentations at major national and international conferences in 2014 (the International Geoscience and Remote Sensing Symposium in Canada and the Earth Observation for Ocean-Atmosphere Interactions Science conference in Italy) and his recent article in the Canadian Journal of Remote Sensing.
The GoMRI community embraces bright and dedicated students like Bryan Hamilton and their important contributions. The GoMRI Scholars Program recognizes graduate students whose work focuses on GoMRI-funded projects and builds community for the next generation of ocean science professionals.
Visit the CARTHE website to learn more about their work.
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This research was made possible in part by a grant from BP/The Gulf of Mexico Research Initiative (GoMRI) to the Consortium for Advanced Research on Transport of Hydrocarbon in the Environment (CARTHE) I and II. The GoMRI is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.
Sehinde, at the Tulane University Coordinated Instrumentation Facility, sits beside the scanning electron microscope he uses to image halloysite nanotubes and oil droplets stabilized by them. (Photo by Chike Ezeh)
An interest in oil spill research led Olasehinde Owoseni from Ile-Ife, an ancient city in Nigeria, to the Louisiana coast. Such a change might seem intimidating, but Sehinde sees it is as a small step toward his greater goal.
His research examines the use of miniscule clay particles for the development of safer and more cost-efficient oil spill remediation technologies.
Sehinde is a chemical and biomolecular engineering Ph.D. student at Tulane University and a GoMRI Scholar with C-MEDS. He explains his research and personal journey as a scientist.
His Path
Sehinde is proud to be a chemical engineer because he feels that transforming natural materials into useful products creates “a vital link between scientific understanding and societal application.” He completed an undergraduate degree at Obafemi Awolowo University – Ile-Ife and began his chemical engineering career at PZ Cussons, an international detergent and cosmetics manufacturer. Working in industry gave him a taste of practical engineering, but he had a deep desire to continue his education. While researching graduate schools, he heard about dispersant technology research at Tulane University led by Dr. Vijay John, director of C-MEDS. Sehinde was eager to take part in the search for more ecofriendly dispersant systems and enrolled in Tulane’s chemical and biomolecular engineering doctoral program. There, he joined the lab of his advisor Dr. John, whose research aims to design the next generation of dispersants.
His Work
Sehinde uses liquid nitrogen to freeze oil droplets stabilized by halloysite nanotubes. Cryogenic imaging of these droplets will allow researchers to visualize the nanotubes and how they attach to the surface of oil dispersed in water. (Photo by Chike Ezeh)
Sehinde’s initial research focused on improving oil dispersants by replacing potentially harmful components with natural materials. Dispersants contain substances that lower surface tension (surfactants) and substances that disperse oil for microbial consumption (solvents). He considered these components’ roles and saw the potential to replace solvents used in existing dispersants with halloysite, a naturally occurring clay composed of tiny nanotubes. “Instead of using completely solid particles, we chose hollow particles that could be filled with surfactant,” he explains. “This is the first time the use of hollow particles has been applied to oil spill remediation.”
Sehinde loaded surfactant into the nanotubes using vacuum suction and then applied them to the surface where oil and water meet. He found that surfactant-loaded nanotubes were more effective at dispersing oil and keeping it dispersed than commercially-available dispersants. The nanotubes released surfactant slowly, creating smaller droplets that are easier for oil-degrading microbes to eat. The nanotubes also linked together across the oil’s surface, which prevented droplets from regrouping into a larger form. Sehinde’s halloysite research resulted in a Langmuir journal article and was featured on the GoMRI website, Study Finds Ecofriendly Clay Delivers and Improves Oil Spill Treating Agents.
Sehinde uses Tulane’s rotary evaporator to load surfactants into halloysite nanotubes through vacuum suction and solvent evaporation. (Photo by Regan Manayan)
The halloysite experiment’s success led Sehinde to consider other ways the clay nanotubes could be used for oil spill response. His current research examines how loading nanotubes with magnetic materials could track oil’s movement through the ocean. The concept is based on nuclear magnetic resonance, which is when atoms in a magnetic field absorb electromagnetic radiation and re-emit it at a specific frequency. Magnetic clay nanotubes applied at the boundary between oil and water may cause oil atoms to respond to a magnetic field differently than bulk ocean water, indicating oil presence. Sehinde is also curious if magnet-loaded nanotubes could be used to help skim surface oil and if loading nanotubes with nutrients could help microbes degrade oil more quickly. “Those are some directions we can go, but we are taking it one thing at a time,” he explains.
His Learning
Working with C-MEDS has shown Sehinde that collaborating and exchanging knowledge are often the driving forces behind scientific discovery. He has enjoyed the C-MEDS research community because it allows him to learn and contribute simultaneously. “I’ve learned a lot about how science moves forward,” he says. “While you learn from people, people also learn from you. You always have to look at new things and think in new ways. This experience taught me how to be a good scientist.” Looking back at what he has learned, his advice to others considering a science career is that “a constant appetite for learning and a passionate commitment to excellence are essential qualities for a scientist.”
Sehinde conducts room temperature imaging of halloysite nanotubes with magnetic materials on the surface. (Photo by Chike Ezeh)
C-MEDS outreach activities have taught Sehinde how to better communicate with young people and stimulate their interest in science and engineering. He participated in middle school and high school outreach visits, explaining why oil spills occur and what might happen if they go untreated. He demonstrated how adding surfactant or particles can help break up oil in water so that the oil mixes with the water. “I did the experiment first,” he explained, “then, I let the students do it so they can see that it’s real – it’s science.” By stimulating student interest in oil spill treatments that incorporate natural materials, Sehinde believes his work to help reduce dispersants’ environmental impacts might gain public support. He had an opportunity to show high school students from a Louisiana fishing community how a single oil spill can have large impacts. This interaction was particularly memorable for Sehinde, “I enjoyed explaining the science and then relating it to their community. That form of outreach has been a really rewarding part of my work.”
His Future
Sehinde’s oil spill research has inspired him to apply his experience in a different field, improving the technology that powers our lives. In the future, he would like to conduct industry research on new and emerging energy systems, “I’d like to create ways to deliver power with minimal environmental impacts and explore alternatives to oil and gas.”
Praise for Sehinde
Dr. John identified determination as the force behind Sehinde’s abilities as a scientist. “He is a highly motivated student,” John said. “He is able to anticipate directions, driven by his own curiosity.” John explained that these characteristics have made Sehinde an important element of his lab, “He has been a joy to work with. The other graduate students in the department view him with much affection and respect. He is a role model for them, mentoring newer students and generating ideas with more senior students, some of which have led to collaborations with my faculty colleagues.”
Despite Sehinde’s strong personal drive, John describes him as being “quiet and scholarly” – someone who speaks through his work. “He thinks very creatively. Oftentimes, when we discuss research and ideas, he surprises me with subtle statements that indicate that he has not only thought of the idea but that he has also done the key experiment to validate his hypothesis,” John explained. “Sometimes, I wish Sehinde would argue a research point with me, but that is simply not his style. He listens, never pushes his opinion, and just quietly does his work. And, when it is done, it is clear that he has thought the problem through.”
John also praised Sehinde’s ability to communicate science effectively. He noted that Sehinde won 2nd place in the American Institute of Chemical Engineers Environmental Division Graduate Student Paper Award, which recognizes outstanding graduate student contributions to environmental protection through chemical engineering.
The GoMRI community embraces bright and dedicated students like Olasehinde Owoseni and their important contributions. The GoMRI Scholars Program recognizes graduate students whose work focuses on GoMRI-funded projects and builds community for the next generation of ocean science professionals.
Visit the C-MEDS website to learn more about their work.
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This research was made possible in part by a grant from BP/The Gulf of Mexico Research Initiative (GoMRI) to theConsortium for the Molecular Engineering of Dispersant Systems (C-MEDS). The GoMRI is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.
Visitors to the Smithsonian Ocean Portal now have the opportunity to learn more 
about oil spills like the Deepwater Horizon. By using the Smithsonian’s newly released interactive tool on oil spill science, they can learn about cleanup efforts, dispersants, where the oil went, seafood safety, and the impacts on the Gulf.
The Portal team, in partnership with scientists funded by the Gulf of Mexico Research Initiative (GoMRI), developed an interactive infographic, The Anatomy of an Oil Spill: Science from the Gulf of Mexico, to visualize the oil spill and describe the research underway in the Gulf.
Visitors can follow a story line from the beginning of the spill to the present, exploring the event and its impacts using information provided by GoMRI research findings.Explore this informative resource and see other GoMRI-related content on the Smithsonian Portal here. GoMRI and the Smithsonian have a partnership to enhance oil spill science content on the Ocean Portal website.
In an acrylic wave tank he designed and built himself at the Johns Hopkins Laboratory for Experimental Fluid Mechanics, Cheng observes a mechanically generated breaking wave and its associated turbulent flows. (Photo credit: Trevor Holmgren)
For Cheng Li, the beauty of our oceans is precious.
He wants to protect that beauty by improving the tracking of and response to oil spills. Using a customized, self-built wave tank, he investigates the interactions between oil, dispersant, and breaking waves. Data from his wave experiments will contribute to better predictions about where and how dispersed oil travels.
Cheng is an engineering Ph.D. student at Johns Hopkins University and a GoMRI Scholar with DROPPS. He explains why he is so invested in oil spill research and the lessons he has learned along the way.
His Path
Cheng has always envisioned a career in science and engineering. However, he did not consider environmental fluid mechanics until he started pursuing graduate school. When applying to Johns Hopkins University (JHU), he heard that Dr. Joseph Katz was an expert in this field, conducting research for many years on the mixing of water with diesel fuel and the effects of turbulence on the breakup and transport of oil. He also learned that Dr. Katz’s research had made notable progress to understand the formation and dynamics of micron-size oil drops in water. Though still an undergraduate at the time, learning about this research sparked Cheng’s interest in fluid mechanics.
As a new JHU graduate student, Cheng began his research studying bottom boundary layer flows off the New Jersey coast. While on board a research vessel, he had an experience that turned his interest in understanding the fluid mechanics of oil and water into a passion. Seasickness sidelined Cheng for several days, but when he recovered and went up on deck for some much-needed fresh air, what he saw stunned him. “The beauty of the sea struck me,” he says. “The astounding power of the waves and the amazing beauty of ocean life helped me realize the vital importance of protecting our oceans.” The recent Deepwater Horizon oil blowout in the Gulf gave that beautiful image additional meaning, and the necessity of oil spill research and recovery became more personal. When Dr. Katz, who was now Cheng’s graduate advisor, became a co-Principal Investigator for the DROPPS oil spill research project, Cheng was happy to be part of his team.
His Work
Cheng aligns a laser at the Johns Hopkins Laboratory for Experimental Fluid Mechanics to form a uniform and collimated laser beam while conducting an in-line holography experiment. (Photo provided by Cheng Li)
Cheng’s research investigates how breaking waves dispel oil slicks with and without chemical dispersant. Sea surface oil slicks can contain harmful toxins and threaten coastlines. Breaking up surface oil into tiny droplets can reduce these hazards, as oil droplets submerge below the surface, keeping slicks away from shore and helping biodegradation. Chemical dispersants amplify this process by weakening the bonds that hold larger droplets together, and breaking ocean waves then separates the oil into smaller droplets and distributes them into the water column. Cheng’s research aims to better understand the physical mechanisms and effects of these processes.
Cheng designed and built a custom wave tank for his experiments that simulates the interactions of waves, oil, and dispersed oil. Made from transparent acrylic for full optical access, the tank measures 20 feet long, 2 feet high, and 1 foot wide and has a piston-type wave plate that can simulate any type of ocean wave, from rolling ripples to powerful plunging breakers. Cheng captures breaking wave actions using a high-speed camera and pushes the camera’s spatial resolution to the limit to observe the formation of small oil droplets. He then generates data based on the waves’ behavior at different time intervals and analyzes the entire process. This data will ultimately describe oil droplet size distribution with and without dispersant.
Cheng’s wave-tank experiments focus on the ocean’s uppermost layer, but he also participated in the DROPPS mesocosm experiment, which replicated the vertical marine environment using tall tanks filled with seawater and phytoplankton. Using lasers and high-speed imaging, researchers from various fields studied interactions of oil droplets rising from the ocean’s bottom with phytoplankton throughout the water column. They found that dispersant created an “octopus-like” body of oil with thin threads and tiny droplets trailing behind the oil, providing a larger surface for biodegrading microorganisms to attach.
While lab work can be challenging, Cheng knows that it will also be rewarding to watch his research enhance real-world oil spill models by forecasting oil paths and identifying the most effective dispersant application strategies. He and his colleagues are slowly uncovering new information about how droplets are physically generated and transported and how dispersant influences droplet size. “Our research intends to minimize the potential damage of future deep-water oil spill disasters,” says Cheng.
His Learning
Cheng explains that DROPPS research is progressive and exciting because it is “amazingly interdisciplinary, combining the valuable experience of expert biologists, chemists, and engineers.” By interacting with other scientists, Cheng constantly learns from and about other scientific fields, which he believes is crucially important to understanding the whole picture. He noted the mesocosm experiment as an example of exciting progress that can result from scientific collaboration. “All of those findings were made possible through interdisciplinary research,” he reflects. “The experiment showed me that interdisciplinary teams can gather far more insight than individual experts alone. It was incredibly rewarding to be a part of it.”
Being on the DROPPS research team is making Cheng’s dream of protecting our seas and oceans a reality. “Since theDeepwater Horizon oil spill, we have learned so much about how oil spreads and how we can safely contain and disperse it,” said Cheng. “I am so pleased that our research will help us more effectively prepare for and deal with oil spills.”
His Future
Cheng is entering the fifth year of his graduate studies and his third year of GoMRI research. In the next couple of years, Cheng will complete his Ph.D. research and pursue either a job in the petroleum industry or a post-doctoral position. Regardless, he is sure of one thing: he wants a career in engineering and environmental fluid mechanics that will build on his research with GoMRI and Johns Hopkins.
Praise for Cheng
Dr. Joseph Katz, a mechanical engineering professor and the Director of the Johns Hopkins University Center for Environmental and Applied Fluid Mechanics, describes Cheng as a “bright, hard-working, and determined student.” Katz reports that Cheng’s research extends beyond a typical Ph.D. thesis and that his elaborate wave tank project exemplifies his “incredible ability to absorb substantial amounts of information from diverse fields and integrate it to produce something new and innovative.”
Katz explains that, as an advisor, delegating tasks and giving advice is easy. However, carrying out those tasks can often be very difficult. Cheng’s ability to handle the high-demand project made him a key element of their oil spill research. “He functioned very well under pressure. When I interact with him, there are two heads involved, not one. It’s not a dictation, it’s an interaction,” says Katz. “I believe this is the beginning of a very successful career as a researcher and scientist.”
The GoMRI community embraces bright and dedicated students like Cheng Li and their important contributions. TheGoMRI Scholars Program recognizes graduate students whose work focuses on GoMRI-funded projects and builds community for the next generation of ocean science professionals.
Visit the DROPPS website to learn more about their work.
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This research was made possible in part by a grant from BP/The Gulf of Mexico Research Initiative (GoMRI) to theDispersion Research on Oil: Physics and Plankton Studies (DROPPS). The GoMRI is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.
Amitesh Saha displays his setup to study the underwater injection of dispersant on an oil plume. (Provided by Saha)
Amitesh Saha is on a mission to find safer alternatives to dispersants currently being used in oil spill cleanup. His research is showing promising results that nanoparticle materials could not only replace dispersants but may also help the marine environment’s response.
Amitesh is a Chemical Engineering Ph.D. student at the University of Rhode Island (URI) and is a GoMRI scholar with C-MEDS. He tells us about his research and its impacts on his science and personal experiences.
His Path
At the time of the Deepwater Horizon oil spill, Amitesh was completing his master’s degree at URI and researching the basic use of particles to stabilize emulsions. However, the oil spill helped him realize that this fundamental science could be the foundation for an important application: oil cleanup. The topic piqued his interest because he felt that it could contribute to developing greener dispersants and stabilizing crude oil in seawater for containment purposes.
Based on his initial research results, Amitesh discussed this new direction with his advisor, Dr. Arijit Bose, who was considering an oil spill research proposal with Dr. Vijay John (Tulane University). After exploring environmentally benign particles as potential alternatives or supplements to conventional dispersants, Amitesh found strong evidence that carbon black particles could be used in oil spill mitigation. He presented the results to Bose who used them as their proposal’s basis. Their research became part of the larger C-MEDS grant focused on improving traditional dispersants and developing new alternatives. Bose also incorporated Amitesh’s work into another successful GoMRI grant led by URI.
His Work
Amitesh Saha uses a Cryogenic Scanning Electron Microscope to investigate the distribution of particles on an oil drop surface in an emulsion. (Provided by Saha)
Amitesh explains that dispersants can help expedite “nature’s way of cleaning an oil spill” as surfactants break crude oil into stabilized tiny drops such that they are suspended in the water column and consumed by oil-degrading bacteria. However, some surfactants do not form very stable emulsions and can be toxic to the marine environment, so Amitesh examined nanoparticles, and specifically carbon black, as an alternative. These nanoparticles form a shell around an oil drop, creating a more stable emulsion and reducing the transfer of harmful polycyclic aromatic hydrocarbons (PAHs) into water.
His results are showing the particles are not only environmentally benign, but also the shells they create also “provide a surface that supports the growth of hydrocarbon-eating bacteria,” Amitesh enthusiastically explains. He also found that nanoparticles are “compatible in both surface and subsea level applications.” His team is conducting experiments with carbon black particles that mimic different scenarios, such as in underwater injections and wave conditions.
A brightfield optical micrograph shows an emulsion of crude oil (O) in seawater (W) stabilized by carbon black particles. (Provided by Saha)
Amitesh says that the day he began working with crude oil samples from the Deepwater Horizon wellhead instead of substitutes laid the foundation for what he considers one of his greatest achievements so far. “For the first time, I was able to form a stable emulsion of crude oil in seawater using a very low concentration of carbon black particles.” These results proved the merit of carbon black for containing open-ocean oil spills. He happily reflects, “I remember clearly how excited Dr. Bose was when I told him about these results!”
Amitesh believes that the implications of his findings may significantly impact future oil spill responses, “We now know that carbon black particles can effectively emulsify oil in various conditions. This shows the potential of nonconventional materials as dispersants.” The GoMRI website featured asummary about their published research in Applied Materials & Interfaces and in Langmuir.
His Learning
Amitesh says that his work with C-MEDS has been a learning experience filled with new opportunities, such as using Cryogenic Scanning Electron Microscopy at Tulane University. For two weeks, the Tulane team trained him, and together they conducted experiments using the instrument to analyze how particles covered oil drops. Being able to visualize this process helped “catapult” him towards new research methods. Amitesh also saw the effects of using seawater rather than plain water in their experiments, “Salts in seawater helped our particles form stable emulsions, showing their ease of delivery in the event of an oil spill.” He brought this knowledge back to his team, set up their own Cryogenic Scanning Electron Microscopy, and incorporated it into their experiments.
Amitesh has learned a great deal about the scientific community through C-MEDS, “I have had the opportunity to collaborate with some of the smartest, most experienced people in my field.” Interacting with scientists in different fields also improved his research, “It’s really wonderful – it widens your horizon; you look at problems in a different light, giving you a better understanding of the problems you are trying to solve.”
His Future
Obtaining successful results in his first graduate project has led Amitesh to truly “fall in love” with his work. He has seen that particles have great application potential. With this framework set, he says that “it’s just a matter of time before we see many sides of using nanoparticles to solve problems.” Amitesh sees himself as a research scientist in industry or academia, using the experience and knowledge he has honed over the years to solve real-world problems. “I look forward to using my skills to the fullest!”
Praise for Amitesh
Dr. Bose speaks highly about Amitesh’s positive and enthusiastic personality and his skills as a scientist, “His can-do approach was critical towards demonstrating this new oil emulsification concept. He is highly creative, hardworking, and always ready to take on new challenges.” Bose added that Amitesh conducts his work with “grace and good humor, qualities that will really help him as he moves on to the next phase of his professional life.”
The GoMRI community embraces bright and dedicated students like Amitesh Saha and their important contributions. TheGoMRI Scholars Program recognizes graduate students whose work focuses on GoMRI-funded projects and builds community for the next generation of ocean science professionals.
Visit the C-MEDS website to learn more about their work.
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This research was made possible in part by a grant from BP/The Gulf of Mexico Research Initiative (GoMRI) to theConsortium for the Molecular Engineering of Dispersant Systems (C-MEDS). The GoMRI is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.
